A preliminary investigation of pre-dispersal seed predation by Acanthoscelides schrankiae Horn (Coleoptera: Bruchidae) in Mimosa bimucronata (DC.) Kuntze Trees

Abstract

Neotropical Entomology 36 (2):197-202 (2007) A. schrankiae depositavam seus ovos sobre os frutos e as larvas, ao eclodirem, perfuravam o exocarpo, alcançando as sementes. A maioria semente. O maior valor da razão "número de ovos/fruto" e a maior porcentagem de sementes predadas foram registrados em abril. A matéria seca total e das sementes não predadas, a proporção de sementes predadas, quadrantes das copas das árvores. PALAVRAS-CHAVE: Fabaceae, Mimosoideae, herbivoria, interação inseto-planta Acanthoscelides schrankiae Horn. feeding in seeds of Mimosa bimucronata (DC.) Kuntze. We investigated the pattern of oviposition and seed exploitation by A. schrankiae the percentage of predated seeds, the total dry weight of fruits and non-predated seeds, the percentage of aborted seeds, and the percentage of non-emergent insects, among different quadrants of the M. bimucronata canopy. To determine the occurring species, the emergence of bruchids and parasitoids was observed in the laboratory, resulting altogether, only in individuals of A. schrankiae and Horismenus sp. (Hymenoptera:Females of A. schrankiae laid their eggs on fruits, and larvae, after emergence, perforated the exocarp to reach the seeds. Most fruits presented one to three eggs and only one bruchid larva was observed in each seed. The highest value of the rate "number of eggs/fruit" and the highest percentage of predated seeds were recorded in April. Dry weight of fruits (total) and seeds (non-predated), proportions of predated seeds, seed abortions, and non-emergent seed predators, were evenly distributed in the canopy.KEY WORDS: Fabaceae, Mimosoideae, herbivory, insect-plant interaction for regulating plant community structure and composition (Janzen 1971) since it acts as a selective force affecting abundance, distribution and evolution of plants (Harper et al. 1970). Among the most important seed predators are the insects, mainly Coleoptera, Diptera, Lepidoptera, Hymenoptera, Thysanoptera and Hemiptera orders (Janzen 1971, Zhang et al. 1997. Bruchid beetles (Coleoptera) (62 genera worldwide) are

Oviposition pattern and within-season spatial and temporal variation of pre-dispersal seed predation in a population of Mimosa bimucronata trees

“…Moreover, larval competition is expected to occur within those seeds with two A. schrankiae eggs (considering successful emergence of larvae) because it is known that M. bimucronata seeds can support the development of only one bruchine (see Appendix A in Menezes et al 2010). Although we show that some fruits received larger egg loads (from four to six eggs), competition at the fruit scale is unlikely because it has been shown that A. schrankiae larvae feed within a single seed until adult emergence (Silva et al 2007). …”

“…Mimosa bimucronata is mentioned as an important agent for restoration of degraded areas (Lorenzi 2000;Brancalion et al 2008), even though this plant is also a weed when dense populations grow in pastures (Lorenzi 2000). The production of mature M. bimucronata fruits (craspedium fruits) occurs almost throughout the year, and the seeds are attacked by the pre-dispersal seed predator A. schrankiae (Silva et al 2007). A. schrankiae females lay most of their eggs on immature green M. bimucronata fruits and after eclosion, larvae perforate the exocarp and reach the seeds (Silva et al 2007).…”

“…The production of mature M. bimucronata fruits (craspedium fruits) occurs almost throughout the year, and the seeds are attacked by the pre-dispersal seed predator A. schrankiae (Silva et al 2007). A. schrankiae females lay most of their eggs on immature green M. bimucronata fruits and after eclosion, larvae perforate the exocarp and reach the seeds (Silva et al 2007). After adult emergence, the attacked seeds do not germinate (Tomaz et al 2007).…”

Relationship Among Phenolic Contents, Seed Predation, and Physical Seed Traits in Mimosa bimucronata Plants

“…This species grows predominantly in damp lowlands, floodplains, and on the margins of rivers and lakes (Lorenzi 2000). Its seeds (located in craspedium fruits) are attacked in the pre-dispersal phase by the beetle Acanthoscelides schrankiae Horn (Coleoptera: Bruchidae) (Silva et al 2007). This insect is known to feed in seeds from 12 plant species, including M. bimucronata (ten Mimosa, one Acacia, and one Schrankia) (Nápoles 2002;Silva et al 2007).…”

“…Its seeds (located in craspedium fruits) are attacked in the pre-dispersal phase by the beetle Acanthoscelides schrankiae Horn (Coleoptera: Bruchidae) (Silva et al 2007). This insect is known to feed in seeds from 12 plant species, including M. bimucronata (ten Mimosa, one Acacia, and one Schrankia) (Nápoles 2002;Silva et al 2007). This bruchid species occurs in the Bahamas, Ecuador, the USA, Mexico, the Dominican Republic, Venezuela, and Brazil (Jesus Romero Nápoles, personal communication).…”